Hardiness - Perennial flax is hardy enough to withstand winters as far north as the Great Lakes, lower New York state and along the Atlantic coast well into New England (zone 4). Although it survives temperatures as low as -20°F, it also thrives in areas where winters are mild as far south as Georgia.
Locating and Planting Flax- Perennial flax is not at all fussy about location, accepting either full or filtered sun or partial shade without complaint. If the soil is light and well-drained a broad range from alkaline to acid is acceptable. Plant home grown or nursery seedlings outdoors in the spring when frost danger is past and the soil can be worked. Plant on a cloudy day, or in the early evening so that the transplants will not have to immediately cope with full sun. Perennial flax has a thin root system and does not transplant easily.
Clean up any garden debris and stones and dig the soil to loosen it down to at least 8 or 10 inches. Dig holes 10 to 12 inches apart that are about the size of the containers the seedlings are in. Remove the seedlings from their containers (unless they are in peat pots) and set them in the holes, taking care that they are the same level with the soil that they were in their containers. Firm the soil gently around the stems and water. After they have become established, pinch the tops of the stems back a bit to encourage them to branch.